The invention relates to a computer tomograph including a measuring unit comprised of an X-ray source and a radiation receiver, in which the X-ray source emits a fan-shaped X-ray beam which strikes an annular radiation received formed of a series of individual detectors, each of which supplies an electric signal corresponding to the received radiation intensity, in which means are provided for the rotation of the X-ray beam about the radiography subject for the purpose of irradiation of a layer of the radiography subject, lying in the fan plane, from various directions, in which a measured valued processing unit is present to which the output signals of the individual detectors for the various irradiation directions are supplied, and which measurand processing unit determines therefrom the attenuation values of predetermined points in the irradiated plane of the radiography subject, and in which an image display device is present for the image-display of the calculated attenuation values, wherein each individual detector is adjustable in such a fashion that it can be brought from a position outside the X-ray beam into a position in which it is impinged upon by the X-ray beam.
In the case of a known computer tomograph of this type, the radiation receiver is mounted on gimbals and that portion of the receiver which is required for the purpose of detection of the X-radiation issuing from the radiography subject is respectively pivoted into the X-ray beam with the aid of guide means. A swiveling motion of the radiation receiver thereby results, and the individual detectors are not respectively perpendicularly impinged upon by X-radiation. In addition, the moved masses are relatively large, which is particularly disadvantageous when short scanning times are desired for which a rapid swiveling motion is required.
In a further known computer tomograph of the initially cited type, each individual detector is adjustably mounted so that it can be selectively moved into the X-ray beam or out of the latter. Indeed, a motion of the entire radiation receiver is thereby avoided; however, the constructional outlay for the adjustment of the individual detectors is very great.